Siftproof automatic bag and method of making



W. J. MCDOWELL Dec. 23, 1952 SIFTPROOF AUTOMATIC BAG AND METHOD OF MAKING Filed Feb. e, 1949 3 Sheets-Sheet l ATTOR N EY Dec. 23, 1952 w. J. MGDOWELL SIFTPROOF AUTOMATIC BAG AND METHOD OF MAKING 3 Sheets-Sheet 2 Filed Feb. 8, 1949 Eiga gwoon/tw: Vu/qm JM.L pme,

@M MW ATTORNEY Dec. 23, 1952 w. J. MGDOWELL 2,622,786

SIFTPROOF AUTOMATIC BAG AND METHOD OF' MAKING Filed Feb. a, 1949 sweets-sheet 3 44 -Tfn" w, pm

ATTORNEY Patented Dec. 23, 1952 SIFTPROOF AUTOMATIC BAG AND METHOD OF MAKING William J. McDowell, South Gate, Calif., assignor to Benj. C. Betner Company, Devon, Pa., a corporation of Delaware Application February 8, 1949, Serial No. 75,121

6 Claims. l

It is an object of this invention to provide a bag having a preformed bottom of the so-called automatic type in which the bottom is siitproof and heat-sealed.

It is a further object of this invention to provide a method of making such bags, which method, for the most part, may be carried out by the use of existing conventional machinery.

The above and other objects will be made clear from the following detailed description taken in connection with the annexed drawings, in which Fig. 1 is a plan View of two superimposed webs showing the fold lines and paste spots,

Fig. 2 shows the Webs of Fig. 1 folded into a gusseting tube and further shows how the tube is shaped at the bottom end,

Fig. 3 is a perspective view illustrating the character of the seal in the inner ply,

Fig. 4 is a perspective view showing the folding of the inner ply after sealing, and

Fig. 5 is a plan view illustrating how the bottom of the inner ply is enclosed within the bottom formed on the outer ply.

The so-called automatic bottom bags have been extremely useful because of their ability to stand upright, when empty, while being conveyed, lled, etc. The nature of this bottom, however, is such that inherently it is not siftproof, and while many efforts have been made to produce a siftproof automatic bottom, none of these has resulted in a product which could be manufactured by any existing equipment.

Referring now to Fig. 1, I show a paper ply It constituting the outer ply of the bag and an inner ply I2 which either is formed of inherently heatscalable material or which has spaced bands of heat-scalable material located to coincide with both the top and bottom of the ultimate bag. Such heat-scalable bands are shown in the patent to Haskell No. 1,983,291. One set of gusset fold lines is indicated at lli, I6 and I8, while the opposite set is indicated at 2li, 22 and 2li. The front Wall 26 lies between the lines I8 and 20, and the rear wall 28 lies between the line 24 and the margin oi the web I. A seam forming strip 3i! lies between the line lli and the opposite margin of the web. As shown, the inner ply l2 is offset slightly from the outer ply Il) so that its longitudinal seam will not coincide with the seam of the outer ply.

Before the plies are superimposed in the tubing operation a series of die cuts 32 are formed in the outer ply it and longitudinal slits 3i are formed adjacent the ends of each of the die cuts. A series of pasted areas are also applied to the inner surface of the outer ply It. Small paste bodies 36 are applied adjacent the mouth end oi the bag to prevent separation of the plies at that point, and such practice is conventional. In addition there are elongated paste bodies 38 running longitudinally of the bag from adjacent the mouth to a transverse paste line running the entire width of the web lil and spaced from the bottom end oi the bag a distance equal to the amount of material going into the conventional diamond fold. This fold is best shown at 42 in Fig. 5.

After the die cutting, slitting and paste applying operations are complete on the outer ply Il), the inner ply l2 is superimposed thereon and the combined webs pass through a conventional tuber, where the tubes are cut off each at the line X--X shown in Fig. l. This has the elect (Fig. 2) of producing a tongue 44 extending slightly beyond the terminus of the inner ply and enables the conventional bag bottomer to grip the outer ply Without gripping the inner ply.

When the tube lengths are severed the bottom end, in the condition illustrated in Fig. 2, is subjected to heat and pressure in the sealed area 4B. This completely seals the inner ply in the area it as illustrated in Fig. 3, but due to the presence of the non-heat-sealable ply l0, the gussets of the inner ply are not secured together in the area it and remain free to spread as shown in Fig. 3. At the same time the tube is transversely scored along lines Y-Y and Z-Z.

Thereafter the tube lengths are fed to a oonventional bottomer which grips the tongue 44 and opens the diamond fold 42 as shown in Fig. 5.

It has been found that due to the fact that the inner ply is free of the outer ply between line Y-Y and the end of the bag while they are secured together by the transverse paste band 4t just inside the line Y-Y, the inner ply takes the form shown in Fig. 4 and drops into that form midway through the opening of the diamond fold, while the outer ply at the bottom is in the form or" an upright rectangle normal to the body of the bag. The sealed area d is not disturbed by this action. It will be noted that the peripheral seal of the interior surfaces of the inner ply form substantially an H-shaped seal having two mutually parallel portions extending across the rectangular bottom, these portions being joined by a third portion at right angles to the parallel portions and running lengthwise the rectangular bottom. The bottom folding operation continues in the conventional manner by folding the portions of the outer ply outside the lines Y--Y of Fig. 5 inwardly upon the bag bottom.

The folding of the bottom is facilitated by a preliminary separation of the gussets, as shown in Fig. 3 either prior to or concomitantly with the gripping of the tongue 44 and the opening of the diamond fold. This is easily accomplished by means of guides placed between the gussets.

It will be noted that the product of this invention is an automatic bag with a completely conventional exterior appearance. At the same time it has a heat-sealed inner ply with the seal sup.- ported by the paper bottom. Also important is the fact that the distribution of superimposed plies in the bottom is substantially uniform and symmetrical whereby the preformed bottom lies substantially in a single plane normal to the axis of the bag body. This enables full realization of the advantages of the automatic bag, plus the tight bottom closure of a heat-sealed square bag.

If a full, two-ply thumb notch is desired at the mouth end, a piece equivalent to the tongue 44 may be removed from the inner ply. An alternative, enabling the bag to be opened by automatic machinery, is to make one face of the bag slightly wider than the other.

I claim:

1. A bag formed from a two-ply gusseted tube, the inner surfaces of the inner ply being sealed around their inner periphery adjacent the bottom end to form an H-shaped fin-type seal, said bag having a pre-formed, rectangular bottom folded against one wall of the tube along a line extending transverse the bag and parallel to the median line of said bottom, the outer ply being formed in a conventional diamond fold in said bottom, the inner ply being free of the outer ply in areas of the diamond fold outside the rectangular bottom and being secured to the outer ply about the periphery of such bottom, the said H-shaped n type seal being folded into two spaced parallel parts lying transverse to the rectangular bottom and a third part lying longitudinally of the rectangular bottom and connecting said two parallel parts.

2. The bag set forth in claim 1 in which the inner surfaces of the inner ply are heat-sealed.

3. The bag set forth in claim 2 in which the inner ply is a lm of thermo-plastic material.

4. The bag set forth in claim 2 in which the inner ply is formed of non-heat-sealable material coated with a band of thermo-plastic material adjacent the bottom end.

5. A method of making bags comprising: forming a two-ply gusseted tube; sealing all contacting inner surfaces of the inner tube together in a narrow band adjacent the bottom end of the two-ply tube While the tube is collapsed, to form an H-shaped n type seal; securing the inner and outer plies together at a distance from the bottom end of the tube substantially equal to the altitude of the tapered portions of a conventional diamond fold while leaving the plies mutually free of each other within such distance; opening the outer ply into a conventional diamond fold, thereby collapsing the sealed end of said inner ply into a rectangular, preformed bottom; and folding the ends of said diamond fold outside the dimensions of said rectangular bottom into superimposed relationship within said dimensions and securing the same in said relationship.

6. A method according to claim 5 in which the opening of the diamond fold is preceded by a separation of the gussets adjacent the bottom end.

WILLIAM J. MCDOWELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,062,265 Haskell Nov. 24, 1936 2,197,112 Piazze Apr. 16, 1940 2,237,327 Bell Apr. 8, 1941 2,353,402 Haslacher July 11, 1944 2,359,190 Avery Sep. 26, 1944 2,377,005 Haslacher May 29, 1945 2,396,565 Gardner Mar. 12, 1946 2,420,212 Volksdorf May 6, 1947 

